In recent years, there has been considerable progress in small, legged robots that can run rapidly and stably over rough terrain. Climbing and maneuvering on a vertical surface presents a more difficult challenge, which robots are just beginning to address. For applications such as surveillance or the inspection of hard-to-reach locations, one would like to have small robots that can climb a variety of hard and soft surfaces unobtrusively and cling for extended periods of time without high power consumption.
Previously developed climbing robots have generally employed either suction cups, magnets, or sticky adhesives to cling to smooth vertical surfaces such as windows and interior walls. None of these approaches is suitable for porous and typically dusty exterior surface such as brick, concrete, stucco or stone. A recent development employing a controlled vortex to create negative aerodynamic lift has been demonstrated on brick and concrete walls (www.vortexhc.com). However, this approach consumes significant amount of power, whether the robot is stationary or moving, unavoidably generates noise, and is difficult to adapt to non-smooth surfaces such as window ledges, corners, and corrugated surfaces. Still other robots employ hand and foot holds in the manner of a human climber.
Observing animals that exhibit scansorial (vertical surface) agility, one can find a variety of methods employed. Larger animals such as cats and raccoons employ strong claws that penetrate wood and bark surfaces. Tree frogs and many insects employ sticky pads. Geckos and some spiders employ large number of hairs that achieve adhesion via van der Waals forces on almost any kind of surface. Other insects, arthropods and reptiles employ small spines that catch on fine asperities. Accordingly, it would be considered an advance in the art to design biologically inspired climbing devices and mechanism.